* Subject: Re: Kinematics * Date: Tue, 30 Aug 1994 23:10:48 -0700 (PDT) [53] * From: "Randy R. Wall" <rrw@ecst.csuchico.edu>Well, I am pretty new to the Kinematics in Imagine but I'll get you started, so that you can experiment. First make three axis, making one and then copy it and paste it down twice. Now press R/a_F to Find Axis.1 and select it and then use R/a_T for the Transformation requester and set it's Z position to 50. Now Find Axis.2 and set it's Z position to 100 in the same manner you did with Axis.1. Now select the bottom Axis and the Axis.1 just above it by using the Shift Key as you select it. Group them together and then click anywhere on the screen to unselect these Axis. Now select the middle Axis.1 and the top axis.2 and group them together. Ok this is a basic bone structure or group, if you select the bottom axis while in Pick Groups mode all of the axis will be selected. So with this I can explain to you SOME simple kinematics...at least enough to get you started.
Ok now go into Pick Objects Mode ( Kinematics will only work in Pick Objects Mode ). Select the bottom axis and and then select Freeze, in the Freeze menu set Rotation World X,Y and Z and OK. Now go and set Constrain and then select the top axis.2 of the group and press M. If you are in the quad view ( all four views showing ) you can go in the top view and rotate your pointer around the axis. You will see that all the axis follow the pointer as you move it, but the bottom one stays stationary and does not rotate with the others. If we unset the Rotation World X,Y, and Z it would follow along with the other axis. Now if we wanted to limit this group more we could do the following:
Set the ALL axis so Rotation World Y, and Z are set, Un-set the bottom axis's Rotations. Now go and select the top axis and try rotating the pointer around the axis in the top view, as you can see the axis now only move along the Y axis or should I say will only rotate on the X axis. As we have limited its movement by only letting it rotate on X. Hit the Spacebar and then R/a_U to undo this and select the Right View Bar.
Now we can make the axis move in a more controllable means. Select the top axis again if its not already, and press R and then X and move the pointer to the right slowly till the axis angle is at 45 degrees. Imagine will tell you this at the top right corner of the menu bar. The top axis will rotate on its X axis. Now press M and move the pointer to the left and slightly down. As you can see the top axis keeps its alignment of X and all the other bones or axis bend to make it look like a finger bending. This may cause a problem if you move to far, but you can either try moving it back and try again or hit the spacebar and then select the middle axis and press R then X and rotate the middle axis into the correct position.
If you wanted to stop the bottom axis from causing this problem you could Freeze its World Tranlations, and then move or rotate the top axis to the position or alignment you want, and Then Un-set the bottom Axis Translations and Rotate its Axis on X to rotate the whole group. Or to do a similar effect, yet keep your top axis free to move and rotate you could rotate the middle axis into the angle you want and then Lock it's X Joint and select the top axis and move or rotate it's X axis. By doing this the bottom and middle axis stay aligned to each, yet still follow the top axis, and leaves the top axis free to manipulate...
Oopps! typo on my part, it should read: Set ALL the axis so Rotation World Y, and Z are set,
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